Microelectromechanical systems include highly miniaturized devices that employ electrical and/or mechanical components. These systems are typically fabricated using integrated circuit batch-processing techniques. There are a number of fabrication technologies, collectively known as micromachining, for producing microelectromechanical systems. One type of micromachining process is surface micromachining. Surface micromachining involves deposition and photolithographic patterning of alternate layers of structural material (typically polycrystalline silicone, termed polysilicon) and sacrificial layers (typically silicon dioxide, termed oxide) on a silicon wafer substrate material. Using a series of deposition and patterning, functional devices are constructed layer by layer. After a device is completed, it is released by removing all or some of the remaining sacrificial material by exposure to a selective etchant such as hydrofluoric acid, which does not substantially attack the polysilicon layers.
Unfortunately, it is a problem in the art of microelectromechanical systems to prevent particle contamination. Particle contamination can potentially ruin an entire system by interfering with the electrical signals and/or mechanical movements of some or all of the electrical and/or mechanical devices. Furthermore, as will be appreciated, such particle contamination has a high likelihood of occurring in areas of the microelectromechanical system that have a high density of surface features, and thereby can potentially cause the most significant harm.